The Houston Texans are feeling good after scoring a franchise-record 57 points in a win over the Tennessee Titans last week.

Now they’ll see if they can keep things up offensively when they face the NFL’s only undefeated team, the Kansas City Chiefs, on Sunday night. The Texans (2-2) understand they can’t rest on what they did last week.

“There were a ton of good things in the game,” coach Bill O’Brien said. “I think our players deserve all the credit. They played very well in the game, but there’s a lot to clean up before we get to … Sunday night.”

Much of Kansas City’s early success can be attributed to the stellar play of veteran quarterback Alex Smith. He’s tied for third in the NFL with eight touchdown passes and is one of three regular starters yet to throw a pick, along with the Patriots’ Tom Brady and the Saints’ Drew Brees. Good company.

He is also completing more than 76 percent of his throws, resulting in a league-best 124.2 passer rating.

“He’s everything you want as a coach,” Chiefs coach Andy Reid said. “This is what we have confidence in, players, coaches, we all have confidence that he does this.”

Smith is prepared for a challenge this week in facing a Texans defensive front featuring J.J. Watt and 2014 top overall pick Jadeveon Clowney. The quarterback is still plenty worried about Watt despite the fact that he doesn’t have a sack four games into the season after missing the last 13 games last year because of back surgery.

“I know the numbers might not be there statwise as far as sacks and things like that, but the plays still show up on film,” Smith said. “He’s tough to block, almost impossible at times … just extremely disruptive up there. He’s a guy that can wreck a game if given the opportunity.”

While the Chiefs (4-0) have an experienced quarterback playing some of his best football in years, the Texans will counter with rookie Deshaun Watson, who has excelled since taking over midway through the opener and is coming off his best game. It’s no surprise to Reid that Watson has played so well early after watching his work last season when he won a national championship at Clemson.

“What he did at Clemson was what we thought he would do here,” Reid said. “But he’s a tremendous football player. He’s got some good players there around him, and he’s utilizing them.”

The Chiefs have won 12 straight AFC West games and 26 of their last 30 overall, the best mark in the NFL in that span. They’ve also been successful against the Texans in recent meetings, going 3-1 since 2013. The biggest win in that span came when they embarrassed the Texans at home with a 30-0 win in the AFC wild-card game in 2015.

Houston’s offense got a boost last week from the return of receiver Will Fuller. He made his debut against the Titans after missing the first three games because he broke his collarbone early in camp. The first-round pick in 2016 had touchdown receptions of 16 and 10 yards for the first multi-TD game of his career.

O’Brien was impressed with how Fuller performed in his first game back.

“He had a good game,” O’Brien said. “He’s a really good route runner. He’s a tough guy. Obviously, great speed. You can line him up anywhere; he knows what to do at every position. Very smart player. Very calm guy. Never gets rattled. Just really good to have him back in there.”